Renewable Engine Fuel And Method Of Producing Same

ABSTRACT

The present invention provides high-octane fuel, and a method of producing same. These fuels may be formulated to have a wide range of octane values and energy, and may effectively be used to replace 100 LL aviation fuel (known as AvGas), as well as high-octane, rocket, diesel, turbine engine fuels, as well as two-cycle, spark-ignited engine fuels.

REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 12/717,480,filed Mar. 4, 2010, which was a continuation-in-part of U.S. patentapplication Ser. No. 12/139,428, filed Jun. 13, 2008, now issued as U.S.Pat. No. 8,049,048, which was a continuation-in-part of Ser. No.11/881,565, filed Jul. 27, 2007, now abandoned, the contents of all ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates in general to an engine fuel and inparticular to a 100 octane aviation fuel.

BACKGROUND OF THE INVENTION

Octane number is a measure of the effectiveness of power production. Itis a kinetic parameter, therefore difficult to predict. Oil companiescompiled volumes of experimental octane data (for most hydrocarbons) forthe Department of Defense in the 1950's. For example, 2,2,4-trimethylpentane (isooctane) has a defined octane number of 100, and n-heptanehas a defined octane number of 0, based on experimental tests. Octanenumbers are linearly interpolated and are generally hard to extrapolate,hence some predictions for mixes can be made only once pure samplevalues are determined.

Automobile gasoline is placarded at the pump as the average of researchand motor octane numbers. These average octane numbers correlate torunning a laboratory test engine (CFR) under less severe and more severeconditions, respectively, and calculating the average octane exhibitedunder these conditions. True octane numbers lie between the research andmotor octane values. Aviation fuel has a “hard” requirement of 100 motoroctane number (MON); ethanol has a MON of 96, which makes its use viableonly when mixed with other higher octane components that are capable ofincreasing the MON to at least 100. Conventional 100 octane low lead(100 LL) contains about 3 ml of tetraethyl lead per gallon.

The inherent energy contained within gasoline is directly related tomileage, not to octane number. Automobile gasoline has no energyspecification, hence no mileage specification. In contrast, aviationfuels, a common example being 100 LL, have an energy contentspecification. This translates to aircraft range and to specific fuelconsumption. In the octane examples above, i-octane and n-heptane hadvalues of 100 and 0, respectively. From an energy perspective, theycontain heat of combustion values of 7.84 and 7.86 kcal/ml,respectively, which is the reverse of what would be expected based onpower developed. Aircraft cannot compromise range due to the sensitivityof their missions. For this reason, energy content is equally importantas MON values.

The current production volume of 100 LL is approximately 850,000 gallonsper day. 100 LL has been designated by the Environmental ProtectionAgency (EPA) as the last fuel in the United States to contain tetraethyllead. This exemption will likely come to an end in the future. In theUnited States, the Federal Aviation Administration (FAA) is responsiblefor setting the technical standards for aviation fuels. Currently, theFAA uses ASTM D910 as one of the important standards for aviation fuel.In particular, this standard defines 100 LL aviation gasoline. Thus anyreplacement 100 LL will likely also need to meet ASTM D910.

Although a number of chemical compounds have been found to satisfy themotor octane number for 100 octane aviation fuel, they fail to meet anumber of other technical requirements for aviation fuel. This is true,for example, for isopentane, 90 MON, and sym-trimethyl benzene 136 MON.Pure isopentane fails to qualify as an aviation fuel because it does notpass the ASTM specification D909 for supercharge octane number, ASTMspecification D2700 for motor octane number, and ASTM specificationD5191 for vapor pressure. Pure sym-trimethyl benzene (mesitylene) alsofails to qualify as an aviation fuel because it does not pass ASTMspecification D2386 for freeze point, ASTM specification D5191 for vaporpressure, and ASTM specification D86 for the 10% distillation point.Table 3 herein shows these test results and the ASTM standard for bothisopentane and sym-trimethyl benzene.

A number of methods are known for making mesitylene from acetone andinclude, for example:

liquid phase condensation of acetone in the presence of strong acids,e.g. sulfuric acid and phosphoric acid, as described in U.S. Pat. No.3,267,165 (1966);

vapor phase condensation of acetone in the presence of a tantalumcontaining catalysts, as described in U.S. Pat. No. 2,917,561 (1959);

vapor phase condensation of acetone in the presence of a catalystemploying phosphates of the metals of group IV of the periodic system ofelements, e.g. titanium, zirconium, hafnium and tin as described in U.S.Pat. No. 3,94,079 (1976);

vapor phase reaction of acetone in the presence of molecular hydrogenand a catalyst selected from alumina containing chromia and boria asdescribed in U.S. Pat. No. 3,201,485 (1965);

vapor phase reaction of acetone using catalysts containing molybdenum asdescribed in U.S. Pat. No. 3,301,912 (1967) or tungsten as described inU.S. Pat. No. 2,425,096; a vapor phase reaction of acetone over aniobium supported catalyst with high selectivity. The catalyst ispreferably made by impregnating a silica support with an ethanolicsolution of NbCl.sub.5 or an aqueous solution of a niobium compound inorder to deposit 2% Nb by weight and by calcining the final solid at550° C. for 18 hours at 300° C. The condensation of acetone producesmainly mesitylene (70% selectivity) at high conversion (60-80% wt) asdescribed in U.S. Pat. No. 5,087,781.

It is known that alkynes can be cyclotrimerized over transition metalcatalysts to form benzene derivatives (C. W. Bird in “Transition MetalIntermediates in Organic Synthesis”, New York, London: Academic Press,1967, pp. 1-29) and U.S. Pat. No. 4,006,149). It is also known in theart to dimerize acetone to form isopentane. This process involves firstdimerizing acetone to form diacetone alcohol which is then dehydrated toform mesitytl oxide. The mesityl oxide then undergoes gas phasereformation hydrogenation to form isopentane.

Although the prior art describes various methods in which acetone can betrimerized to form mesitylene in acid media, as well as various gasphase reactions in which acetone is trimerized in acidic heterogeneouscatalytic surfaces such as silica gel, there still exists the problem ofcontrolling the (1) extent of reaction (dimerization as opposed totrimerization) as well as (2) the selectivity of the reaction(minimization of unreacted side products) while maintaining (3) highthroughput.

It is an object of the present invention to provide fuels for aircraftwhich replace 100 LL aviation gasoline. It is a further object of thepresent invention to provide high energy renewable fuels for use inturbines and other heat engines by the same methodology; the energycontent and physical properties of the renewable components beingtailored to the type of engine to be fueled.

It is another object of the present invention to provide a binarymixture of components which meet the technical specifications foraviation fuel of 100 LL octane. It is another object of the presentinvention to provide a non-petroleum based aviation fuel as areplacement of 100 octane which meets the technical specifications ofthe Federal Aviation Administration for 100 octane aviation fuels. Alsodisclosed is a process for the production of a biomass-derived fuelusing bacteriological fermentation to produce the components of a binarychemical mixture which satisfies the technical specifications for 100octane aviation fuel. It is yet another object of the present inventionto provide a process for the production of a new chemical-based 100octane aviation fuel from renewable sources.

SUMMARY OF THE INVENTION

In one embodiment, the present invention provides a fuel comprised of abinary mixture of components, which provides an effective aviation fuelmeeting the requirements of the Federal Aviation Administration. Thismay comprise (a) at least one aromatic hydrocarbon, and (b) at least oneisoparaffin having from 4 to 6 carbon atoms. The high octane aviationfuel may include the aromatic hydrocarbon in an amount of at least about60 wt %; and the isoparaffin is present in an amount of at least about15 wt %.

The high octane aviation fuel preferably includes no more than about 85wt %; and the isoparaffin is present in an amount of no more than about40 wt %. The aromatic hydrocarbon preferably is sym-trimethyl benzene(mesitylene). The mesitylene preferably is present in an amount of atleast about 70 wt %. In combination with isopentane, the isopentanepreferably is present in an amount of at least 15 wt %.

Further, the present inventors have performed extensive research inorder to identify viable processes for efficiently convertingbiomass-derived sugars to ethanol or acetic acid to acetone via abacterium fermentation process, then converting the ethanol tomesitylene in a dehydration reaction, or converting the resulting aceticacid to acetone if need be, and then converting the acetone tomesitylene and isopentane, the basic components of the fuel.

There is also provided a method of producing bio-mass derivedhigh-octane fuel, wherein the biomass is selected from the groupconsisting of sugars, celluloses, lignins, starches, andlignocelluloses. Alternatively, the biomass is selected from the groupconsisting of hard woods, grasses, corn stover, sorghum, corn fiber, andoat hulls, which are pretreated with enzymes or strong acids to breakany hemicellulose chains into their sugar monomers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of the motor octane number (MON) as a function of wt %of mesitylene for a binary mixture of isopentane and mesitylene.

FIG. 2 is a graph of the Reid vapor pressure as a function of the wt %of mesitylene for the binary mixture of isopentane and mesitylene.

FIG. 3( a) is a process flow diagram illustrating a process ofextracting 6C (six carbon-containing) sugars from sugar biomassfeedstocks.

FIG. 3( b) is a process flow diagram illustrating a process ofextracting 6C (six carbon-containing) sugars from starch/grain biomassfeedstocks.

FIG. 3( c) is a process flow diagram illustrating a process ofextracting 6C (six carbon-containing) sugars from lignocellulosicbiomass feedstocks.

FIG. 4( a) is a process flow diagram illustrating an ethanolic processwherein 6C sugars are fermented first to ethanol, and then to aceticacid.

FIG. 4( b) is a process flow diagram illustrating an ethanolic processwherein 6C sugars are converted to ethanol.

FIG. 4( c) is a process flow diagram illustrating an acetic processwherein 5C and 6C sugars are converted to acetic acid.

FIG. 4( d) is a process flow diagram illustrating an acetic processwherein 5C and 6C sugars are fermented to produce lactic acid, andlactic acid is then fermented to acetic acid.

FIG. 5 is a process flow diagram illustrating a process wherein theacetic acid produced in the processes shown in FIGS. 4( a), 4(c) and4(d) is converted to acetone, the acetone is then converted tomesitylene and isopentane, and finally combined to produce the fuel ofthe present invention.

FIG. 6 is a process flow diagram illustrating the process wherein theethanol produced in the process shown in FIG. 4( b) is converted toacetone, the acetone is then converted to mesitylene and isopentane, andfinally combined to produce the fuel of the present invention.

FIG. 7 is a process flow diagram illustrating a process of converting 6Csugars to the fuel of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the present invention provides a fuel comprised of fullyrenewable components, i.e., components derived from biosources. The fuelmay comprise (a) one or more low carbon esters derivable from ethanol,(b) one or more pentosan derivable furans, (c) one or more aromatichydrocarbons derived from acetone or propyne, (d) one or more C₆-C₈straight chain alkanes derivable from polysaccharides and (e) one ormore bio-oils derived from plant germ. In addition, the fuel may containtriethanolamine, which provides lubricity. Amines have been known toincrease lubricity in internal combustion engines; triethanolaminehaving such a property when used with the other renewable components.

With regards to component (a), i.e., low carbon number esters, it ispreferable to utilize esters having a carbon number of 1-4, such asethyl acetate, butyl acetate or propyl acetate. Most preferably, ethylacetate is used, as ethyl acetate provides an increase in the fuel'svapor pressure, essential for cold weather operations. These low carbonnumber esters are derivable from ethanol, using processes such as directreaction with acetic acid in the presence of sulfuric acid. Further, theacetic acid can be directly derived from ethanol, if desired. All ofthese components can be derived from kernel corn, switchgrass or othercellulosic or sugar based materials.

With regards to component (b), i.e., pentosan derivable furans, it ispreferable to utilize substituted furans. Most preferably, 2-methylfurans are used. The pentosan derivable furans are derived from cornstalks, stalks of other grains, and potentially, grasses. Specificfurans are used as octane and energy increasing components.

With regards to component (c), i.e., aromatic hydrocarbons, unlikeconventional petroleum-based fuels, the present invention comprisesaromatic hydrocarbons derived from acetone, a fully renewable source.Most preferably, the aromatic hydrocarbon is mesitylene. Mesitylene canconveniently be prepared by the trimerization of acetone or propyne;acetone can be readily prepared from biomass, and propyne can beextracted from natural gas. Mesitylene is preferred, since the acetoneor propyne reaction “stops” at the trimer, which makes the conversionhigh due to lack of significant side-reactions. Mesitylene can be usedas an octane and energy enhancing ingredient.

With regards to component (d), i.e., straight chain alkanes in the C₄ toC₁₀ range, the alkanes are derived from biomass, specificallypolysaccharides derived from biomass. Straight chain alkanes have thelowest octane number of a given set of alkane isomers; the more branchedthe molecule, the smoother combustion (higher octane) the moleculeexhibits when tested. Preferably C₅ to C₉ straight chain alkanes areutilized. Most preferably C₆ to C₈ straight chain alkanes are includedin the fuel. These straight chain alkanes act as octane depressantswithin the fuel. Most preferably, the straight chain alkanes are one ormore chosen from n-pentane, n-hexane, n-heptane, n-octane, and n-nonane.

Lower straight chain alkanes, such as n-pentane, n-butane, propane andbelow, have too low of a boiling point to be useful as a main componentof the developed fuel. Higher straight chain alkanes, such as n-nonane,n-decane and above, have too high of a carbon-to-hydrogen moleculefraction (>0.444). This high fraction leads to incomplete combustion inheat engines and coking. Straight chain alkanes are used to suppress theoctane of a given fuel, while maintaining a high energy content per unitvolume. Higher alkanes can be used in diesel and jet turbineapplications.

With regards to component (e), i.e., bio-oils derived from plant germ,these components may be derived from various plant sources. For example,the bio-oil may include soybean oil, rapeseed oil, canola oil or cornoil, palm oil, and combinations thereof. Most preferably, corn oil isutilized as the bio-oil component because of its enhancement of energy,fuel's physical properties, and lubricity properties. Corn oil isderived directly from the corn germ.

Further, optionally, the fuel may additionally contain component (f),i.e., triethanolamine. The inclusion of triethanolamine in the renewablefuel provides the advantage of lubricity at low concentrations, as wellas effective octane improvement due to the combustion inhibitionproperties of the nitrogen moiety. Triethanolamine can be derived fromammonia and ethylene, both of which can be conveniently produced frombiomass.

It was unexpectedly discovered that, by combining the above components(a)-(f) in the weight ranges called for herein, a completelynon-petroleum-based fuel, fully derivable from renewable biomasssources, could be obtained. Further, it was discovered that the fuelcomponents could be conveniently adjusted to produce an appropriate airto fuel ratio for application in a heat engine. In the case of aircraftengines, that value was 14.2 to 1, based on mass. Further, it wasunexpectedly discovered that this renewable fuel can be formulated tohave a very high octane, e.g., up to 160 MON, by varying the octaneincreasing ingredients, such as the furans, with the energy increasingcomponents such as mesitylene and corn oil.

Alternatively, the renewable fuel of the present invention can beformulated to have a much lower octane rating, such as 84 MON, which canbe, for example, utilized as an automotive fuel. In particular, a highenergy, octane depressant (component (d)), such as n-heptane, can beadded to the fuel to obtain a lower octane rated fuel for use inconventional automotive and aviation applications. Another method offormulating a lower octane fuel, known as “derating”, includes thesubstitution of acetone or tetrahydrofuran or other low octaneingredients for the ethyl acetate, while increasing the energy content.

Representative examples of the fuels (identified in the column labeled“Formulation”), which have been prepared in the laboratory, are shownbelow in Table 1.

TABLE 1 “Composition Matrix for Formulations” Ethyl 2-Methyl CornFormulation Acetate Furan Mesitylene n-Heptane Oil High Octane 17.5%17.5% 60.0% 0.0% 5.0% AvGas 100LL 13.1% 13.1% 45.0% 25.0% 3.8%Replacement Auto Gas 9.0% 10.0% 36.0% 40.0% 5.0% Turbine Fuel 8.0% 24.0%60.0% 0.0% 8.0% Turbine Fuel 2 0.0% 0.0% 0.0% 63.0% 37.0% Diesel Fuel0.0% 0.0% 0.0% 63.0% 37.0% Rocket Fuel 0.0% 0.0% 60.0% 35.0% 5.0%

Preparation Example 4-Cycle Engine Fuel

17.5 grams of ethyl acetate were mixed with 17.5 grams of 2-methylfuran. 60 grams of mesitylene were then added, followed by 5 grams ofcorn oil, to form 100 grams of fuel of the present invention. Themixture was stirred until all components were dissolved. The resultingsolution was then analyzed, and found to have an effective MON of 142,and an optimum mixture ratio of 14.2 based on mass. This fuel has beeneffectively demonstrated in low and high compression reciprocatingaviation engines.

Test Examples

In order to determine the characteristics of the renewable engine fuelof the present invention (representative examples of which are describedas “Invention Formulation” in Table 1 above), the present inventorsprepared the following fuels of the present invention (denoted in Table2 as “100 LL Replacement” and “High Octane AvGas”), and conductedcalorimetric tests thereof. In particular, calorimetry was conducted ina Parr combustion bomb. Octane measurements were done by variablecompression ratio engine testing under more severe conditions to assessMotor Octane Number (MON).

Bulk calorimetry accurately determines the energy content (heat ofcombustion) of a given component or mixture. MON values were conductedby Intertek Caleb Brett® under the ASTM D2700M methodology.

Through thermophysical analysis and initial formulation, a series offour- and five-part mixtures according to the present invention, asshown in Table 2 below, were prepared, which have been shown throughtesting to be capable of directly replacing conventional 100 LL AviationFuel and conventional High Octane Aviation Fuel. The compositioninformation for these fuels is found in Table 1.

Upon further testing in the laboratory, through the use of a bulkcalorimeter, the present inventors have confirmed that the test resultsfor the renewable fuel of the present invention (denoted as 100 LLReplacement in Tables 1 and 2) are comparable with the currently used100 LL aviation fuel properties. The characteristics of these renewablefuels of the present invention, obtained through testing as describedabove, are shown in Table 2. Also shown in Table 2 are the physical andchemical properties for conventional 100 LL aviation fuel, forcomparison, shown as the second column under “Current Fuel”.

TABLE 2 “Comparison of Current 100LL Aviation Fuel and Aviation Fuels”Current 100LL High Octane Characteristic Units Fuel Replacement AvGasMotor Octane ≧101 107 142 Number Net Heat of kcal/cc ≧7.49 7.96 7.99Combustion Air to Fuel Ratio w/w ≧14.00 15.13 14.20 Average EmpiricalC₈H₁₈ C_(9.1)H₁₅O_(0.7) C_(9.8)H₁₄O Formula Flame ° K ≧1906 2130 2140Temperature Density at 15° C. kg/m³ ≧720.3 831.4 882.1 Tetraethyl leadgPb/l 0.56 0 0 Sulphur % mass ≦0.05 0 0 Initial Boiling ° C. 65 65 PointFreezing Point ° C. ≦−58 −66 −58 Final Boiling ° C. ≦168 165 165 PointHodges Vapor kPa 37 to 87 58 60 Pressure Visible Lead mg/100 ml ≦3 0 0Precipitate Flame Color Orange Orange Orange

In another aspect, ethanol-based renewable fuels are provided, which inone respect can be derived from biosources. Furthermore, two of thecomponents can be directly synthesized from ethanol; which makes thistechnology complementary to existing and future ethanol plants. The rawmaterials for each of the components are polysaccharides or germ oils insome form; these have current and projected market prices

In particular, a high-octane aviation fuel is provided, which iscomprised of (a) at least one aromatic hydrocarbon, and (b) at least oneisoparaffin having from 4 to 6 carbon atoms. This biomass-derived fuelhas been experimentally demonstrated to have a high-octane rating, andis ideal for use in aviation applications. For example, the fuel of thepresent invention may be utilized as a replacement for the conventional100 LL (low lead) aviation fuel used throughout the world in privateaviation, as well as for use in turbine (jet) engine applications.

In a preferred embodiment, the aromatic hydrocarbon is sym-trimethylbenzene (mesitylene), also known as 1,3,5-trimethylbenzene. Variousexperimental studies were conducted to determine the effect ofmesitylene concentration on MON, and in particular the optimal weightpercent range thereof that provides the desired MON. The results ofthese tests, which applied the test standards under ASTM D2700 motoroctane number in lean configurations, are shown in FIG. 1, wherein theX-axis denotes mesitylene concentration in weight percent, and theY-axis denotes MON of the fuel.

Since the minimum motor octane number required for 100 LL octaneaviation fuel is 99.5, it can be seen from FIG. 1 that all blendsgreater than about 70 wt % mesitylene meet that specification. Inparticular, when the aromatic hydrocarbon (mesitylene) is present in anamount of from about 60-85 wt %, a MON of from 96-105 is obtained. Whenthe mesitylene constitutes 70-85 wt % of the fuel composition, the MONis observed to be 100 to 105. When the fuel contains mesitylene in anamount of 75 wt %, an MON of about 101-102 is obtained.

Further tests were carried out according to ASTM D5191 to determine theReid vapor pressure as a function of concentration (wt %) of mesitylenefor a binary mixture of isopentane and mesitylene. The 0% and 100% (purechemicals) were not tested. The results of these tests are illustratedin FIG. 2, wherein the X-axis denotes the concentration of mesitylene inweight percent, and the Y-axis denotes the Reid vapor pressure in psi(pounds per square inch). The Reid vapor pressure requirement of 100 LLoctane aviation fuel is between 5.5 and 7.1 psi. As illustrated in FIG.2, mesitylene concentrations of from about 70-85 wt % meet the Reidvapor pressure requirement for 100 LL octane aviation fuel. It should benoted that neither pure mesitylene nor pure isopentane meet thisspecification.

The isoparaffin of the above mentioned high-octane aviation fuel ispresent in the fuel in an amount of from about 15-40 wt %, morepreferably 15-30 wt %. The isoparaffin is preferably a normally liquidisoparaffin, such as isopentane.

In an alternative embodiment, a fuel is provided, further comprising astraight chain alkane. Preferably, the straight chain alkane is a 3carbon alkane, i.e., propane. Further, in this embodiment, rather than abranched chain 5 carbon alkane, such as isopentane as described above, astraight chain alkane, such as pentane is used. Such a fuel ispreferably used as an automotive fuel.

In a further alternative embodiment, a fuel is provided, furthercomprising a straight chain alkane. Preferably, the straight chainalkane is a 3 carbon alkane, i.e., propane. Such a fuel is preferablyused as a turbine engine fuel in aviation applications.

The present inventors conducted further tests according to six ASTMstandards (methods) to determine various characteristics of puremesitylene, pure isopentane, Swift 702 pure fuel according to thepresent invention (comprised of 83 wt % of mesitylene and 17 wt %isopentane) and conventional 100 LL aviation fuel. The results of thesecomparative tests are illustrated in Table 3 below:

TABLE 3 ASTM Swift 100 Method Test Mesitylene Isopentane 702 spec D2700Motor Octane 136 90.3 104.9 ≧99.5 Number D909 Supercharge 170 92.3 133.0130.0 ON D5191 Vaper Pressure ≦5.5 ≧7.1 5.7 5.5 to 7.1 D2386 Freezing Pt−49 −161 −63 ≦58 D86 10% 165 28 65 ≦75 Distillation Pt. D86 End 185 28165 ≦170 Distillation Pt.

Applicants unexpectedly discovered from these tests that addingisopentane to mesitylene in a certain concentration as called for hereinincreases the vapor pressure, lowers the freezing point, and lowers the10% distillation point of mesitylene to within the ASTM standard asshown in Table 1. Applicants also unexpectedly discovered that addingmesitylene to isopentane to form a 100 octane aviation fuel raises themotor octane number of the isopentane (as compared to pure isopentane),raises the supercharge octane number of isopentane (as compared to pureisopentane), and lowers the vapor pressure of isopentane (as compared topure isopentane) to within the ASTM D910 specification.

The present inventors have further developed a method of producingbio-mass derived high-octane aviation fuel, comprising a first step ofextracting 5C and 6C sugars from the biomass, and fermenting theextracted sugars with a microorganism or mutagen thereof to produce amixture of metabolites comprising acetone and butanol. In particular,various processes may be utilized to ferment the sugars extracted fromthe biomass, as illustrated in FIGS. 3( a)-3(d). Then, as illustrated inFIGS. 4( a)-4(d), the sugars are fermented to produce ethanol or aceticacid. This fermentation step is preferably conducted in an anaerobicreactor in the absence of oxygen.

Various experimental tests were carried out to determine whichmicroorganisms are most capable of converting the biomass-derived sugarsto ethanol and acetic acid. The results of these tests, as well as theconditions under which these tests were carried out, are illustrated inTable 4 below.

TABLE 4 Fermentation Fastest Acetate Sugars Temperature DoublingProduced Microorganism Fermented pH (° C.) Time (Hours) (g/L) MoorellaGlucose, 7.2 57 6 25 Thermoaceticum Xylose Thermoanaerobacter Glucose6.5 66 3 43 Kivui Morrella Glucose, 7 55 10 20 Thermoacetica Xylose,Lactic Acid Moorella Glucose, 6.5 60 10 30 Thermoautotrophica Xylose,Lactic Acid Moorella Glucose, 6.9 58 6 25 Thermoaeticum Xylose MoorellaGlucose, 6.9 56 6 35 Thermoautotrophicum Xylose ThermoanaerobacterGlucose 6.9 45 6 20 thermosaccharolyticum Moorella Glucose, 6.9 60 6 90Thermoaceticum Xulose

In view of the results of the tests discussed above, preferably, themicroorganisms (MO's) used to carry out this fermentation process areone or more of moorella thermoaceticum, thermoanaerobacter kivui,moorella thermoacetica, moorella thermoautotrophica, moorellathermoaeticum, moorella thermoautotrophicum, thermoanaerobacterthermosaccharolyticum, moorella thermoaceticum. saccarophagus degradansstrain 2-40, more preferably, thermoanaerobacter kivui, and/or moorellathermoaceticum are utilized, as they have been experimentally shown toproduce the greatest acetone yield. However, selection of the MO's isdependent upon the particular biomass feedstock chosen, and can include,for example, clostridium and variants thereof.

The general classes of biomasses used as the base feedstocks in themethod of production provided herein are those from which 5C and 6Csugars may be derived, such as sugars, celluloses, lignins, starches,and lignocelluloses. Preferably, hard woods, grasses, corn stover,sorghum, corn fiber, and/or oat hulls are utilized. To increase theefficiency of the fermentation process, preferably, these feedstocks arepretreated with enzymes or strong acids to break any hemicellulosechains into their sugar monomers.

Alternatively, in a preferred embodiment, ethanol may be produced from aplant material using the bioorganism saccharophagus degradans, strain2-40. In particular, saccharophagus degradan is first grown in a firstportion of the plant material. Then, protein is harvested fromsaccharophagus degradans, strain 2-40, and mixed with a second portionof the plant material and yeast in an aqueous mixture to produceethanol.

The ethanol is then converted in whole or in part to acetone.Preferably, the ethanol is converted to acetone in the presence of ironoxide catalysts, or converted to acetone in the presence of zincoxide-calcium oxide catalysts and water vapor. In addition, preferably,the acetone is separated from any remaining ethanol and/or otherbyproducts not converted to acetone in these processes.

In a second step of the method, the acetone is separated from butanol,ethanol or other solvents in the metabolite mixture. In particular, themetabolites of acetone, butanol and ethanol produced in the first stepare separated from the fermentation mixture when concentrations thereofexceed 2 to 3 wt %. It has been unexpectedly discovered that that thisavoids possible poisoning of the microorganism or mutagens thereof. Thismay be performed using any conventional prior art process. In apreferable embodiment, fractional distillation is utilized to performthis function.

In a third step, a portion of the resultant acetone produced in thesecond step is dimerized to form isopentane. Any conventional processmay be utilized to carry out this dimerization step. Preferably,however, dimerization of acetone is carried out in a catalytic reactionto yield isopentane. Most preferably, this dimerization step is carriedout in a gas phase catalytic reaction.

In a fourth step, another portion of the acetone derived in the secondstep described above is trimerized to form mesitylene. As in the thirdstep above, the trimerization process may be carried out using anyconventional trimerization process. Preferably, the trimerization ofacetone is carried out in the gas phase by reacting acetone withsulfuric or phosphoric acid at elevated temperatures. Further, thistrimerization step is preferably carried out in the presence of acatalyst.

The trimerization catalyst preferably contains at least one metalselected from the group consisting of Row 4 transition metals (V, Cr,Mn, Fe, Co, Ni, Cu), Row 5 transition metals (Nb, Mo, Ag), and Row 6transition metals (W), all as fully developed oxides.

Preferably, Column 2A alkaline earth metals (Mg, Ca, Sr, Ba), and Column1A alkaline metals (Na, K) as the developed oxides, are effective aspromoters or co-catalysts in the trimerization catalysts.

The catalyst is preferably comprised of three portions, (1) a catalystsubstrate or base with a defined surface acidity and surface area, (2)the catalyst itself which is preferably dispersed on the substrate as adeveloped oxide and, optionally, (3) a promoter or co-catalyst which ispreferably an alkaline species which tailors the overall acid propertiesof the catalyst ensemble.

In order to tailor the catalyst for the three controlled parametersabove, the surface acidity is preferably controlled. Changing to a moreacidic catalyst substrate such as silica gel or amorphous silica or amore neutral catalyst substrate such as alumina have produced unexpectedresults due to surface acidity.

In low flow systems, it is preferred to use a catalyst in bead form.These catalysts are prepared by using a base of alumina or silicacatalyst base, in bead form, which can be soaked with a defined volumeof impregnating solution. The volume of impregnating solution is definedby the apparent bulk density (ABD) of the catalyst base. Theconcentration of the impregnating solution can be adjusted such that adefined amount of solution is in contact with the catalyst base. Forexample, 107.05 g of alumina beads are contacted with 27.83 g of ferricnitrate nonahydrate dissolved to make 100 ml of impregnating solution.The alumina beads have an ABD of 0.7146, hence the dry volume is 150 ml.The 100 ml of impregnating solution just covers the particular catalystbase. The base and the solution are left in contact for one hour. Themix is dried in a drying oven at 200° C. until at constant weight. Thedried catalyst is calcined in a calcining furnace overnight at 700° C.In this example, 3.58 g of stable iron oxide is deposited on 150 ml ofbase, which is more conveniently expressed as 675 g per cubic foot.

In high flow rate systems, monolithic catalysts are preferably used. Inthe monolithic catalyst, a defined slurry of catalyst compound is placedin contact with a continuous ribbon of a metallic substrate bonded to analumina wash coat. The slurry is dried, then calcined similar to theprocess above. The slurry concentration and temperatures for drying andcalcining are chosen to ensure the correct deposition and fixation ofthe defined oxide. The deposited catalyst is expressed in units of gramsper cubic foot similar to the method discussed above. Preferred highflow rate catalysts include manganese nitrate and niobium oxide.

Lastly, the mesitylene with the isopentane derived in the third andfourth steps described above are mixed in the appropriate proportions toform synthetic high-octane aviation fuel. Specifically, the proportionsof these components are mixed in the weight percentages described above.The process steps utilized to carry out the third through fifth stepsare illustrated in FIGS. 5 and 6.

An alternative overall process view is illustrated in FIG. 7. In thisalternative embodiment of the present invention, natural gas or gasproduced from biomass is converted to propane, propane is converted topropyne (methylacetylene), and propyne to mesitylene and isopentane. Itshould be noted that this reaction process is similar to the method ofmanufacture discussed above using acetone. However, no water isgenerated, and the reaction is all gas phase.

It should be recognized that the alternative embodiment fuels mentionedabove comprising, for example, pentane or propane, are manufacturedusing the above described process. However, the pentane and propanecomponents can be derived from acetone instead of, or in addition to,the mesitylene and isopentane components in a similar manner. Further,if desired, conventional fuel additives, such as surfactants, viscosityimprovers, anti-icing additives, thermal stability improver additives,and metal de-activators to suppress the catalytic effect which somemetals, particularly copper, have on fuel oxidation. However, theseadditional components must be selected with care so as to ensure thatthey have no effect on the MON, Reid vapor pressure, etc.

In another embodiment mesitylene can be made in a process including (1)fermentation of a biomass to form ethanol, (2) a dehydration reaction ofethanol to form acetone and water, (3) the separation by distillation ofunreacted ethanol from water and acetone, and (4) the gas phase reactionof acetone to form mesitylene. For the reaction step ethanol can bemetered out and then vaporized. The ethanol vapor can be superheated to350° C. at 100 psig and then the superheated vapor is passed through areactor containing a catalyst bed. A preferred catalyst is zincoxide/calcium oxide, for the ethanol to acetone reaction.

After being decompressed to atmospheric pressure, the gas is liquefiedin a condenser and collected. Preferably, a dry ice condenser liquefiesany vapors that pass through a primary condenser that are condensabledown to minus 78° C. The raw product can then be distilled, unreactedethanol (overheads) being separated from acetone and water (bottoms),and through a gas phase reaction to form mesitylene from the acetone.The ethanol (overhead stream) can be recycled to the reactor.

As long as there is no acetone present, water can be separated frommesitylene via a phase separator because of their mutual low solubility.The water (heavy phase) can then be drawn off and disposed of.Mesitylene can be sampled and stored. The condensed ethanol can berecycled back to the reactor feed tank. The condensed acetone can berecycled as well.

Although specific embodiments of the present invention have beendisclosed herein, those having ordinary skill in the art will understandthat changes can be made to the specific embodiments without departingfrom the spirit and scope of the invention. The scope of the inventionis not to be restricted, therefore, to the specific embodiments.Furthermore, it is intended that the appended claims cover any and allsuch applications, modifications, and embodiments within the scope ofthe present invention.

1. A 100 octane aviation fuel comprising: (a) 70-85 wt % ofsym-trimethyl benzene (mesitylene); and (b) 15-30 wt % of isopentane,wherein the fuel has a motor octane number of 99.5 or greater, and aReid vapor pressure of from 5.5 to 7.1 psi.
 2. A 100 octane aviationfuel consisting essentially of: (a) 70-85 wt % of sym-trimethyl benzene(mesitylene); and (b) 15-30 wt % of isopentane, wherein the fuel has amotor octane number of 99.5 or greater, and a Reid vapor pressure offrom 5.5 to 7.1 psi.
 3. A 100 octane aviation fuel consisting of: (a)70-85 wt % of sym-trimethyl benzene (mesitylene); and (b) 15-30 wt % ofisopentane, wherein the fuel has a motor octane number of 99.5 orgreater, and a Reid vapor pressure of from 5.5 to 7.1 psi.
 4. (canceled)5. A high octane aviation fuel comprising: (a) 60-85 wt % ofsym-trimethyl benzene (mesitylene), and (b) 15-40 wt % of isopentane,wherein the fuel has a motor octane number of 99.5 or greater, and aReid vapor pressure of from 5.5 to 7.1 psi. 6-11. (canceled)
 12. Theaviation fuel of claim 5, wherein the mesitylene is present in an amountof between about 70 to 85 wt %.
 13. The aviation fuel of claim 5,wherein the isopentane is present in an amount of between about 15 to 30wt %. 14-22. (canceled)
 23. A high octane fuel comprising: (a) 70-85 wt% of sym-trimethyl benzene (mesitylene); and (b) 15-30 wt % ofisopentane, wherein the fuel is an aviation fuel having a motor octanenumber of 99.5 or greater, and a Reid vapor pressure of from 5.5 to 7.1psi.
 24. A 100 octane aviation fuel comprising: (a) 70-85 wt % ofsym-trimethyl benzene (mesitylene); and (b) 15-30 wt % of isopentane,wherein the fuel has a motor octane number of greater than 99.5, and aReid vapor pressure of from 5.5 to 7.1 psi.